Yeah, but Natasha was a slut herself. So why would she behave that way. It's not explained how she suddenly turned full circle and became a completely different person. She knows exactly where Sveta is coming from. Even today people in the town still talk about how much of a slut she was, when she was younger, and it's not so surprising that Sveta is following in her footsteps. Every single woman in their family has a high sex drive. Natasha sleeps around, her sister Luda sleeps around and her other daughter Anya sleeps around. They all do it, and yet apparently Natasha has a total blind spot when it comes to Sveta doing the same thing.
If she herself never fucked around, if nobody else in the family fucked around, you could understand why she might behave that way towards only Sveta.
I don't think it's far fetched for certain mothers in Russia to condemn their daughters, rather than say the older men who have been having sex with them. I just think it's far fetched for Natasha, because unlike most of those women, she has personal experience of being that woman being condemned for having a high sex drive. She still is that person, and what makes it even more ludicrous is that Sveta is well aware of Natasha cheating on Vladimir herself, and Natasha knows that she knows. All she would need to do, is threaten to tell Vladimir and Natasha would forget all about throwing her out. I mean why wouldn't she do that, if her mother was being a total hypocrite?
How can Natasha threaten Sveta with anything, when she knows her own dirty secrets? If that comes out, her marriage would be over. So why would she ever take the risk?